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West Antarctic glacier loss has 'passed point of no return,' studies show (video)

Antarctic Melt

This undated handout photo provided by NASA shows the Thwaites Glacier in West Antarctic. Two new studies indicate that part of the huge West Antarctic ice sheet is starting a slow collapse in an unstoppable way. Alarmed scientists say that means even more sea-level rise than they figured.
(NASA via Associated Press)

Two scientific studies released Monday say five glaciers on the West Antarctic Ice Sheet are undergoing a slow but irreversible collapse and the end result could be a rise in sea levels by about 4 feet.

Scientists originally believed the collapse of the glaciers in the Amundsen Sea region of the West Antarctic Ice Sheet would take thousands of years, reports the Los Angeles Times. The studies say the melting is occurring much more rapidly than expected and now could occur within 200 years.

"We have passed the point of no return," says Eric Rignot, a glaciologist at the University of California at Irvine and the lead author of the study, which has been accepted for publication in the journal Geophysical Research Letters. The glaciers' retreat "will also influence adjacent sectors of the West Antarctic Ice Sheet, which could triple this contribution to sea level," he said during a briefing Monday. This would amount to a global average of three to four meters of sea-level rise.

Slate reports the glaciers in question flow into Pine Island Bay in the Western Antarctic, which leads to the Amundsen Sea. More from Slate:

These glaciers flow into the bay, creating ice shelves that float on the water. The line where the ice leaves the land and floats on the water is called the grounding line. Warm water has been melting the underside of the floating ice, which has been pushing the grounding line farther inland. ... Up until recently it's been difficult to understand just what is going on under the glacier, including the exact position of the grounding line. The scientists used radar data to measure the way the ice moves to find it. As the ice moves from land to sea, it floats on the water. As the tides go up and down, the ice moves up and down with it, and this allows them to determine just where the ice moves out into the water--the grounding line. Over time, the grounding lines are moving inward, which increases the water's ability to melt the ice.

The studies show the warming water contributing to the ice melt is tied to many factors, "including a warming of the planet driven by emissions from human activity and depleted ozone that has changed wind patterns in the area," the Los Angeles Times reports.

A rise in sea level of less than 2 feet would have a "chaotic impact" on the California coast, the Times reports. If the entire ice sheet disappeared, sea levels would rise a "catastrophic" 15 feet.

"This is really happening," Thomas P. Wagner, who runs NASA's programs on polar ice and helped oversee some of the research, said in an interview. "There's nothing to stop it now. But you are still limited by the physics of how fast the ice can flow."

The reports on the glaciers are more bad news in regard to the enviroment. Last week, a government report said the effects of global warming already are being felt in the United States and include more severe heat waves, droughts and rising sea levels.

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